1. Field of the Invention
The present invention relates to uninterrupted power supply (UPS) system, and particularly to a UPS which has solar powered battery charger.
2. Description of Related Art
Referring to FIG. 1, a block diagram of a conventional UPS is shown, together with a power source 100 and an electrical device 700. The UPS includes a filter 200, a transfer switch 300, a battery charger 400, a storage battery 500, and an inverter 600. The power source 100 is connected to one input of the transfer switch 300 and an input of the battery charger 400 via the filter 200. An output of the battery charger 400 is connected to another input of the transfer switch 300 via the storage battery 500 and inverter 600 in turn. An output of the transfer switch 300 is connected to the electrical device 700. The power source 100 charges the storage battery 500 via the battery charger 400. If the power source 100 fails when the electrical device 700 is in use, the transfer switch 300 controls the storage battery 500 to directly supply power to the electrical device 700.
However, the storage battery 500 is useful for only a limited amount of time, and if the power source 100 does not start working again during that time, the electrical device 700 will have no power.
What is desired, therefore, is to provide a UPS which has a back-up, solar powered battery charger to charge the storage battery therein.